The present invention is directed to a volute type centrifugal pump and more specifically to a volute pump having an impeller with two reversely angled Vanes each having a semi-cylindrical projection on the trailing surface adjacent the end thereof.
Volute type pumps are generally old and well known in the art wherein an impeller is rotatably driven within the volute by a motor for pumping fluid through the housing along a spiral flow path from an inlet concentric with the impeller to an enlarged outlet. If an impeller is used wherein a pair of oppositely extending straight, smooth impeller vanes are secured to a hub in a common plane, a considerable amount of cavitation will occur on the trailing surfaces of the vanes, thereby causing mechanical vibration and loss of efficiency. The separation of the fluid from the vanes at the cutwater also causes a substantial amount of turbulence which increases the drag on the impeller.